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Item Late-gestation heat stress impairs daughter and granddaughter lifetime performance(Elsevier Inc on behalf of the American Dairy Science Association, 2020-08) Laporta J; Ferreira FC; Ouellet V; Dado-Senn B; Almeida AK; De Vries A; Dahl GERecords of late-gestation heat stress studies conducted over 10 consecutive years in Florida were pooled and analyzed to test the hypothesis that maternal hyperthermia during late gestation impairs performance of the offspring across multiple generations and lactations, ultimately impeding the profitability of the US dairy sector. Dry-pregnant multiparous dams were actively cooled (CL; shade of a freestall barn, fans and water soakers, n = 196) or not (HT; shade only, n = 198) during the last 46 d of gestation, concurrent with the entire dry period. After data mining, records of 156 daughters (F1) that were born either to CL (CLF1, n = 77) or HT dams (HTF1, n = 79) and 45 granddaughters (F2) that were born either to CLF1 (CLF2, n = 24) or HTF1 (HTF2, n = 21) were used in the analysis. Life events and daily milk yield for 3 lactations of daughters and granddaughters were obtained. Milk yield, reproductive performance, and productive life data were analyzed using MIXED and GLIMMIX procedures, and lifespan was analyzed using PHREG and LIFETEST procedures of SAS (SAS Institute Inc., Cary, NC). Milk production of HTF1 was reduced in their first (2.2 kg/d), second (2.3 kg/d), and third lactations (6.5 kg/d) compared with CLF1. More HTF1 were culled before first calving, and the productive life and lifespan of HTF1 were reduced relative to CLF1 (4.9 and 11.7 mo, respectively). The granddaughters (HTF2) born to HTF1 produced less milk in their first lactation (1.3 kg/d) relative to granddaughters (CLF2) born to CLF1. More HTF2 were culled before first breeding relative to CLF2; however, productive life and lifespan were not different between HTF2 and CLF2 animals. An economic analysis was then performed based on the number of heat stress days, dry cows per state, and the aforementioned impairments on daughters' lifespans and milk production. Collectively in the United States, the economic losses for additional heifer rearing cost, reduced productive life, and reduced milk yield of the F1 offspring were estimated at $134, $90, and $371 million per year, respectively. In summary, late-gestation heat stress exerts carryover effects on at least 2 generations. Providing heat abatement to dry-pregnant dams is important to rescue milk loss of the dam and to prevent losses in their progeny.Item Measuring hoof horn haemorrhage in heifers: A history.(Elsevier B.V., 2024-06-27) Laven R; Laven LUnderstanding the aetiology and pathogenesis of claw-horn disease (CHD) is essential for developing prevention/treatment programmes. Haemorrhages in the hoof horn (i.e. white line/sole haemorrhages) are an important part of the pathogenesis of CHD, being precursors to and predictors of lesions such as white-line disease and sole ulcer. Understanding haemorrhage development can provide useful information about the aetiology and pathogenesis of CHD. The development of hoof horn haemorrhages is best studied in cattle without previous claw-horn damage, as previous history of damage can markedly alter the hoof's response to stressors. Since the early 1990s, many prospective studies of the risk factors associated with CHD have been undertaken in late pregnant and early lactation heifers, which have a low risk of having had CHD but which are exposed to the same risk factors as lactating cows. Those studies have used a range of methods to assess hoof horn haemorrhages, with the principal focus, particularly initially (but also more recently), being on measuring lesion severity. However, as the science developed it became clear that measuring lesion extent was also important and that combining severity and extent in a single measure was the best approach to assess hoof horn haemorrhages. Studies of hoof horn haemorrhage in heifers have significantly increased our understanding of CHD, demonstrating the importance of housing and the relative lack of importance of post-calving nutrition. Most importantly, they have shown the importance of parturition as a risk factor for CHD, and how parturition interacts with other risk factors to accentuate their effect. The use of such studies has decreased in recent years, despite recent research showing that we still have much to learn from prospective studies of hoof horn haemorrhages in heifers.Item The transfer of passive immunity in calves born at pasture(Elsevier Inc and the Federation of Animal Science Societies Inc on behalf of the American Dairy Science Association, 2022-07) Mason WA; Cuttance EL; Laven RACalf and dam separation is an area of growing public interest, and timely separation is also a practical challenge for pastoral farmers to achieve for all calves. Very few studies have investigated the success of leaving calves with their dams in pastoral conditions, so this observational study assessed serum total protein (STP) in calves born at pasture and left to suckle from their dams for up to 24 h. It also investigated failure of transfer of passive immunity (FPT) once calves had been provided colostrum from the farmer and some factors that may contribute to the risk of FPT. Over 2 years, 8 farms (4 in the North Island, 4 in South Island of New Zealand) were involved in an observational study where cows and calves were observed for 24 h a day for 2 wk per farm. Observers recorded the time from birth to first suckling, number of suckling events, time of calf removal from the dam, and ambient temperature. Calves were blood sampled on arrival at housing, before receiving colostrum from the farmer (d 1), and again 2 d later (d 3) to test for STP concentration. On d 1, 689 calves had blood samples collected, at a median of 11.5 (interquartile range 5.6 to 19.2) hours postbirth. Of these, 283 calves [41.1%; 95% confidence interval (CI) 37.4 to 44.9%] had STP >52 g/L (proportion by farm ranged from 10 to 78%). On d 3, 680 blood samples were collected, of which 16.0% (95% CI 13.5 to 19.0) had FPT (STP ≤52 g/L) with proportion by farm ranging from 2.5 to 31.6%. The FPT risk at d 3 in calves that did not suckle before housing was 2.91 (95% CI 2.04 to 4.13) times the risk in calves that suckled. For every hour longer postbirth that it took for a calf to have its first suckling event, odds of FPT at d 3 increased by 1.21 (95% CI 1.08 to 1.36) times, and compared with calves that only suckled once, calves that suckled 2, 3-5, or >5 times had 0.42 (95% CI 0.15 to 0.99), 0.35 (95% CI 0.15 to 0.76), and 0.10 (95% CI 0.005 to 0.47) times the odds of FPT, respectively. For every 1-percentage-point increase in the Brix % of the colostrum, the odds of FPT decreased by 33% (95% CI 24- to 42). Calves that suckled in the paddock and were fed colostrum with ≥22% Brix had the highest STP, and lowest odds of FPT, of any suckling/Brix % combination. There was a trend for STP to be greater in calves that suckled in the paddock and fed <22% Brix compared with calves that did not suckle in the paddock and fed ≥22% Brix. However, the calves in the former group also tended to have a greater risk of FPT at d 3, and a greater STP variability. There were very large between-farm variabilities for rates of suckling, colostrum feeding, and FPT risk that urgently require further investigation for calves born at pasture.Item Suckling behavior of calves in seasonally calving pasture-based dairy systems, and possible environmental and management factors affecting suckling behaviors.(Elsevier Inc and the Federation of Animal Science Societies (FASS) Inc on behalf of the American Dairy Science Association, 2022-07) Cuttance EL; Mason WA; McDermott J; Laven RAIn recent years, interest has been increasing in whether farmed animals are able to live a reasonably natural life, with one particular area of concern being calf-dam separation. The objectives of this study were to monitor the timing and frequency of suckling behavior of calves left on pasture to suckle their dams for up to 24 h (interquartile range 4.0-15.5 h) and to investigate possible risk factors that may contribute to any variability seen. Over 2 yr, a convenience sample of 8 farms (4 in the North Island, 4 in the South Island of New Zealand) were involved in an observational study where cows and calves were observed for 24 h a day over a 2-wk-long period per farm. During the observation period, farmers continued to remove calves at the same frequency they normally did (which ranged from once a day to 4 times a day). Cows (between 2 and 12 yr old) and calves were observed from a scissor lift in or beside the calving paddock. Cows had numbers written on them, and observers used binoculars and spotlights. Observers recorded the length of stage 2 labor, time of birth, standing, and first suckling, number of suckling events, time of calf removal from the dam, temperature where the cows were grazing, and size of the grazing area they were calving in. Dams were body condition scored before calving, and their age was extracted from farm records. A total of 697 calves were observed during the study. A total of 444 of 697 calves [63.7%; 95% confidence interval (CI) = 60.0-67.3%] suckled in the calving paddock (farm range 40.0% to 90.2%). Of the 444 calves that suckled in the calving paddock, 407 (58.4%; 95% CI 54.6-62.1%) suckled within the first 6 h after birth (farm range 33.0% to 83.6%). Individual risk factors associated with the hazard rate ratio (HR) for time to first suckling event were time to standing (calves who took more than 1.3 h to stand had a longer time from birth to first suckle) and age of the dam [compared with calves that were born from dams >7 years of age, calves born to dams that were 2-3 and 4-7 yr of age had a 1.49 (95% CI 1.07-2.06) and 1.19 (95% CI 0.89-1.60) HR, respectively, for time from birth to first suckle in the calving paddock]. Farm risk factors associated with the HR of suckling were frequency of calf collection [calves that were born on farms that collected calves once a day suckled earlier than calves on farms that removed calves more than once a day (HR 1.52; 95% CI 1.25-1.84)] and temperature [a minimum temperature of <10°C within 6 h of a calf being born was associated with a 0.69 (95% CI 0.53-0.89) hazard of suckling in the calving paddock]. We observed very large farm variability that urgently requires further investigation if pasture-based farms are ever to adopt a system where calves remain with their dams for longer than 24 h.Item A review of dystocia in sheep(Elsevier B.V., 2020-11-01) Jacobson C; Bruce M; Kenyon PR; Lockwood A; Miller D; Refshauge G; Masters DGThis review aims to describe the nutritional and non-nutritional factors that may affect parturition and dystocia in sheep. Dystocia is associated with fetopelvic disproportion, uterine inertia, failure of the cervix to fully dilate, malpresentation and disease or congenital defects in lambs. Dystocia can result in lambs that are born dead, or lambs that survive parturition but sustain birth injury including central nervous system damage. Dystocia risk is increased with high or low birthweight lambs, high (fat) or low liveweight ewes, and small first parity ewes. Other factors implicated include low muscle glycogen, pregnancy toxaemia, mineral imbalance causing hypocalcaemia, and a lack of antioxidant nutrients. Addressing these risks requires differential nutritional management for single and multiple bearing ewes. There is also evidence for stress and environmentally related dystocia. The stress related hormones cortisol, adrenaline and ACTH play a major role in the initiation and control of parturition in the sheep indicating a need for adequate supervision during lambing, provision of adequate feed and shelter at the lambing site, and small flock size to reduce physical and environmental stress. Hormonal control of parturition can be further disrupted by xenoestrogens or phytoestrogens in clovers and medics. Oestrogenic plants are still widely grown in mixed pastures but should be not be grazed by pregnant ewes. There is clearly a genetic component to dystocia. This is partly explained by incompatibility in physical size and dimensions of the ram, ewe and lamb. A rapid reduction in dystocia through direct genetic selection is problematic with low heritability of dystocia and some of its indicator traits such as lambing ease. This review provides broad interpretation of the literature, but conclusions are not definitive with widespread inconsistency in reported results. Further research is required to investigate dystocia under commercial production conditions, and this should be complemented by focussed studies under controlled conditions. Priorities include defining the fitness of the ewe to lamb, the role of stress and environment on parturition and the use of indicator traits to select for ease of birth.Item Growth, milk production, reproductive performance, and stayability of dairy heifers born from 2-year-old or mixed-age dams(Elsevier Inc and Fass Inc on behalf of the American Dairy Science Association, 2021-11) Handcock RC; Lopez-Villalobos N; Back PJ; Hickson RE; McNaughton LRKeeping replacement heifers that were the progeny of primiparous cows mated by artificial insemination enhances rates of genetic gain. Previous research has shown that heifers that were the progeny of primiparous cows were lighter at birth and grew at a slower rate to first calving compared with heifers born to multiparous dams. Furthermore, heifers that were heavier before first calving produced more milk than did lighter heifers. This study aimed to determine whether there were body weight, milk production, or reproductive disadvantages for heifers born from primiparous compared with multiparous dams. Data comprised body weight records from 189,936 New Zealand dairy heifers. Dams were allocated to 4 groups according to their age: 2 yr old (n = 13,717), 3 yr old (n = 39,258), 4 to 8 yr old (n = 120,859), and 9 yr or older (n = 16,102). Heifers that were the progeny of 2-year-old dams were lighter from 3 to 21 mo of age than heifers that were the progeny of 3-yr-old and 4- to 8-yr-old dams. The progeny of 2- and 3-yr-old dams produced similar milk solids yields (± standard error of the mean) during their first lactation (304.9 ± 1.6 and 304.1 ± 1.5 kg, respectively), but more than that of 4- to 8-yr-old dams (302.4 ± 1.5). Furthermore, the progeny of 2-yr-old dams had similar stayabilities to first, second, and third calving to that of the progeny of 4- to 8-yr-old and ≥9-yr-old dams. Reproductive performance, as measured by calving and recalving rates was similar in first-calving heifers of all age-of-dam classes. Additionally, second and third calving rates were similar for the progeny of 2- and 3-yr-old dams. Interestingly, the progeny of dams ≥9 yr old had the lowest milk solids production in first (297.8 ± 1.6 kg), second (341.6 ± 1.8 kg), and third lactations (393.2 ± 2.4 kg). Based on the results of this study, keeping replacements from dams aged 9 yr and over could not be recommended. Furthermore, heifers born to 2-yr-old dams were lighter but produced more milk than heifers from older dams, in addition to having superior genetic merit.Item Behavior changes in grazing dairy cows during the transition period are associated with risk of disease : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Manawatū, New Zealand(Massey University, 2020) Hendriks, StaceyThere is growing interest in the use of behavior data derived from accelerometers as a potential measure of animal health, however, research determining the optimal use of these devices and the interpretation of data derived from them, is lacking, particularly in grazing systems. The aims of this thesis were to understand: 1) data management considerations that need to be taken into account when using accelerometer devices to measure behavior in a research setting; 2) environmental and other potentially-confounding variables that can influence cow behavior and, therefore, the interpretation of behavior data; 3) ‘normal’ behavior of clinically-healthy grazing dairy cows during the transition period, and; 4) changes to behavior of grazing dairy cows experiencing varying degrees of hypocalcemia and hyperketonemia. To do this, data from 4 separate parent experiments were collated to generate a database containing detailed phenotype data, including, but not limited to, measures of cow performance (e.g., milk production and composition, body weight and body condition score), cow health (e.g., energy and protein metabolites, minerals, liver enzymes, and immune markers in blood), and cow behavior (e.g., lying behavior and activity derived from triaxial accelerometers). My review of the appropriate use of leg-mounted accelerometers to monitor lying behaviors of dairy cows indicated that applying editing criteria to remove errors in lying behavior data caused by erroneous movements of the leg (e.g., scratching and kicking) can improve the accuracy of data derived from accelerometers for recording daily lying bouts (LB); however, has little to no impact on the accuracy of lying time. Lying behavior data must be edited using a suitable LB criterion where the interest is in studying both lying time and LB. My results indicated that inclement weather, parity, and physiological state are important variables that influence behavior in their own right and must be considered in subsequent analyses. Interestingly, when comparing my results with lying behaviors previously reported in housed cows, my results indicated that grazing dairy cows engage in similar lying behaviors to housed cows before and at the time of calving, while postcalving, grazing cows spend less time lying. Furthermore, grazing dairy cows displayed greater behavioral synchrony (i.e., cows engaged in the same behaviors simultaneously) compared with reports in housed cows. These postcalving differences highlight the importance of assessing behavior within the farming system of interest. My results also indicated that cows alter their behavior in response to ill health, whereby grazing dairy cows experiencing clinical hypocalcemia (without paresis) and hyperketonemia [with severe negative energy balance (NEB)] altered their behavior before, at the time of, and after disease diagnosis compared with healthy cows. My results indicated that behavioral differences between cows classified into 3 blood calcium groups [clinically-hypocalcemic (without paresis), subclinically-hypocalcemic, and normocalcemic] were transient. On the day of calving, clinically-hypocalcemic cows (without paresis), were less active, spent more time lying, and had more frequent LB compared with subclinically-hypocalcemic and normocalcemic cows; however, changes in behavior were short lived and were no longer present by 2 d postcalving. My results indicate that observed differences in behavior associated with hypocalcemia are small and may not be biologically significant as a metric to discriminate between hypocalcemic and normocalcemic cows. On the contrary, changes in behavior over time and within cow may allow differences between hypocalcemic and normocalcemic cows to be more easily discerned than using mean values of lying behavior and activity at a specific time point. My findings indicated that a relative increase in the number of steps taken within cow compared with a baseline period 2 wk precalving was positively associated with blood calcium concentrations postcalving. Further, my results indicated the behavioral differences between cows classified into 3 energy status groups [Hi–Hi = high non-esterified fatty acids (NEFA) and high β-hydroxybutyrate (BHB); Hi–Lo = high NEFA and low BHB, and; Lo–Lo = low NEFA and low BHB] occurred up to 2 wk before calving. During the 2 wk before calving, cows identified as Hi–Hi were more active, spent less time lying, and had fewer LB than the other 2 energy status groups. Interestingly, similar to the hypocalcemia work, my results indicated that a relative increase in the number of steps taken within cow during the 2 wk before calving was associated with lower odds of developing hyperketonemia with NEB; therefore, greater increases in activity before calving were associated with improved health outcomes postcalving in both studies. My results suggest that relative changes in behavior, in particular, step activity, might be an improved metric to discriminate between clinically-healthy grazing cows and cows experiencing a subclinical metabolic disease. My research provides an improved understanding of the associations between cow behavior and health, particularly for grazing dairy cows. This information provides a base for further exploring the potential for behavior and activity measures to identify cows experiencing ill health during the transition period. Future work should focus on continuing to improve our understanding of associations between behavior and disease, particularly in grazing dairy cows. Using within-cow behavior measures and determining how these data could be interpreted so that farmers could be alerted to sick animals and make actionable decisions on farm, should be the focus of future studies.Item A study of circulating neutrophils and exosomes associated with innate immune function in the periparturient grazing dairy cow : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatū, New Zealand(Massey University, 2017) Crookenden, Mallory AnnDairy cows are at greatest risk of infectious and metabolic disease during the periparturient period. This period of three weeks either side of calving is also known as the transition period due to the transition into lactation. This thesis had several aims; one was to characterise innate immune function during the transition period in grazing dairy cows by investigating molecular changes in circulating neutrophils and to assess if common on-farm management strategies (pre-calving feeding level and body condition at calving) were able to influence these molecular changes. Next, metabolic stress on neutrophil function was assessed by establishing a model of cows divergent in metabolic health status. This model was further utilised with the aim to investigate nanoparticles (exosomes), which are regulators of innate immune function and indicators of disease state. To address these aims blood was collected from pasture-fed transition dairy cows. Cellular and molecular methods used included cell and exosome isolation, reverse transcriptase (RT)-quantitative PCR, RNA sequencing, cell culture, and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results indicated that grazing dairy cows experience a change in innate immune function during the transition period, reflective of reduced functional capacity of the immune system to overcome infectious agents. This altered function was similar to that experienced by housed cows fed a total mixed ration, which adds evidence to support that the dysfunction is a natural part of the transition into lactation at calving. These results also indicated that the functional changes could be influenced by nutrition status, feeding level, and metabolic stress. Analysis of exosomes isolated from the blood of transition cows indicated that these particles carried cargo indicative of metabolic state during the transition period and that they had the ability to alter target cell processes (gene expression, protein expression, and cell proliferation). The conclusions from this thesis increase our understanding of transition cow immune function and how it is influenced by nutrition and cow metabolism. These data are particularly relevant for grazing dairy cows and the findings will contribute to on-farm recommendations and the improvement in animal health and well-being. iiiItem Some effects of oxytocin on in vitro preparations of uterine muscle : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Veterinary Science of Massey University(Massey University, 1967) Rees, Humphrey GethinNo abstractItem The induction of calving using betamethasone : and the pharmacological activity of selected formulations having different rates of absorption : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University(Massey University, 1982) MacDiarmid, Stuart CampbellA series of experiments was undertaken in cows to study the disposition and duration of activity of selected formulations of the synthetic corticosteroid betamethasone (BM). The aim was to select a combination of formulations which would be suitable for use in a two-injection treatment regimen designed to induce premature parturition in cattle. In an initial experiment, 10 cows each received a subcutaneous injection of 20 ml of 2 mg/ml aqueous suspension of BM, 10 received 2 ml of a 20 mg/ml suspension and a further 10 cows served as saline-treated controls. The BM formulations differed only in their solids:vehicle ratio. Plasma BM, cortisol and glucose concentrations, and differential blood cell counts were studied for 3 days before, and for 19 days after, treatment. The 2 mg/ml suspension produced a markedly higher peak plasma BM concentration than the 20 mg/ml suspension. However, plasma BM levels tended to be maintained for longer by the suspension having the higher solids:vehicle ratio. The administration of BM resulted in depression of early-morning cortisol concentrations, elevation of plasma glucose levels, and elevation of circulating neutrophil numbers. The magnitude and duration of these changes was related to the solids:vehicle ratio of the injected suspensions, with the more concentrated formulation producing effects of greater duration. A second experiment involved 9 cows which were divided into 3 groups, each of which was treated at a dose rate of 0.1 mg/Kg with sodium phosphate solution or a 2 mg/ml BM suspension or a 20 mg/ml BM suspension. Over a period of several weeks each cow received its allocated formulation by each of 3 routes; intravenous, intramusuclar and subcutaneous. The bioavailability of the BM suspensions was low and the solids:vehicle ratio exerted a profound effect on the rate at which the steroid was absorbed. The disposition curves of the BM solution were similar regardless of the route of administration and the plasma half-life values of BM sodium phosphate, estimated from 3 experiments in each of 3 cows, were 5.64, 6.06 and 6.43 hours. Ten cows were included in a third experiment. They were treated by subcutaneous injection with 2 ml of a 10 mg/ml BM suspension; a preparation intended for use in the induction of calving. Mean plasma concentrations of BM and glucose were elevated above pre-treatment values for 4 days and 8 days respectively. Mean plasma cortisol levels were profoundly depressed for 2 weeks and in some individuals showed no signs of returning to normal 4 weeks after treatment. Two field trials, involving 619 and 553 cows respectively, were conducted to assess the suitability of BM formulations for the induction of premature calving in commercial dairy herds. In the first trial, the mean stage of pregnancy at which cows were treated was approximately 250 days. Cows received an initial injection of either 2 ml of a 10 mg/ml suspension of BM, 2 ml of a 15 mg/ml BM suspension or 4 ml of a 5 mg/ml suspension of dexamethasone trimethylacetate (DTMA). All cows which had not calved within 10 days of this initial treatment received a 12.5 ml dose of a 2 mg/ml suspension of BM. In comparison with those cows treated with DTMA, significantly fewer cows treated with the concentrated BM suspensions required a second corticosteroid injection. In all other respects, such as calf mortality, incidence of retained foetal membranes and maternal illnesses, the results of the treatments were not significantly different. The 10 mg/ml BM suspension was therefore deemed to be suitable for use in the induction of calving. The second field trial confirmed the suitability of the 10 mg/ml suspension as an initial treatment to induce calving. Cows which had not calved within 7 days of the initial treatment were injected with 20 mg of BM, either as a 2 mg/ml suspension or as a 2 mg/ml solution of the sodium phosphate ester. After the second steroid injection, those cows which had received the more rapidly absorbed BM solution calved sooner than those which had been treated with the 2 mg/ml suspension. The results of these studies clearly showed that the duration of activity of BM suspensions could be prolonged by increasing their solids:vehicle ratio. It was also shown that a treatment regimen consisting of an initial injection of a 10 mg/ml BM suspension, followed 7 to 10 days later by an injection of a more rapidly absorbed BM formulation, was suitable for the induction of calving as currently practised in New Zealand.